Rannunculus Anglais - Station Alpine Joseph Fourier

Approaches / Methods: Climatic parameters and concentrations of antioxidants are being
measured throughout the year. The objective is to determine the conditions which induce the
greatest accumulation of antioxidants in S. alpina and to observe the resulting effects on stress
resistance, leaf survival over winter and on flowering. The concentrations of ascorbate are
increased in the presence of the acid L-galactonic γ lactone, a precursor in the synthesis of
ascorbate. Concentrations of glutathion are decreased in the presence of DL buthionine
sulfoximine, an inhibitor of the synthesis of glutathion. Leaves containing varying
concentrations of anti oxidants are exposed to low and high temperatures coupled with high
light intensities to study the role of antioxidants in stress tolerance.
Expected Results: Modification of the foliar concentration of antioxidants in vivo allows
measurement of the role of anti oxidants in stress tolerance. In particular, a low concentration
of ascorbate and glutathion will show if these anti oxidants are necessary for the protection of
S. alpina against high light intensities, low temperatures or high temperatures. Similarly, it
will be possible to determine if ascorbate is necessary for the survival of leaves of S. alpina
under the snow pack over winter allowing photosynthesis and early flowering. A high (or
low) concentration of antioxidants in R. glacialis will show their role in protecting leaves
from the same stresses, and in particular to high temperatures. We hope to understand if a
high concentration of antioxidants favours resistance in the face of global climatic change and
if antioxidant protection systems can ameliorate the survival of plants in the case of
continuing increases in temperature in alpine regions.
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